Semiconductor devices include one or more integrated circuits that can be used to store data, process electronic signals, etc. Such semiconductor devices are used in virtually all modern electronic devices. There are several different types of semiconductor devices used in modern electronics including, for example, memory devices, electronic signal processors, devices for capturing or acquiring images, etc. Each of these semiconductor devices typically comprises a plurality of transistors, which can be used as gates or switches for electrical signals.
One particular type of transistor is the field effect transistor. In a field effect transistor, electrical current is capable of flowing through the transistor between what is referred to as a “source” contact and a “drain” contact. The current flows across what is referred to as a “channel region” between the source and the drain. The electrical resistance between the source and the drain may be altered by subjecting the channel region to an electrical field. The source, drain, and channel region are often formed in a surface of a semiconductor material, such as a surface of a semiconductor substrate. To apply an electrical field to the channel region, a “gate” (which is essentially an electrical contact) is located adjacent (e.g., over) the channel region, and an electrical charge may be applied to the gate. For example, if each of the source, drain, and channel comprises a region in a substrate, an electrical charge may be applied to the gate by applying a voltage between the gate and the substrate. The magnitude of the electrical field present in the channel region and, hence, the electrical resistance between the source and the drain, is at least partially a function of the magnitude of the charge on the gate. A higher electrical resistance in the channel region may be used to represent a “1” in binary code, and a lower electrical resistance may be used to represent a “0” in binary code, or vice versa. By selectively applying a charge to the gate, the channel region between the source and the drain is caused to exhibit higher and lower values of electrical resistance, and the transistor is caused to be selectively characterized as exhibiting either a 1 or a 0 value.
A memory device, for example, may comprise an array of memory cells, each of which may comprise at least one transistor for storing a 1 or a 0 value in the memory cell. When electrical power to the memory device is interrupted, however, the data in any transistor in which an applied voltage was used to electrically charge the gate thereof may be lost as the voltage dissipates after power interruption. Such memory cells that do not retain data therein without continued power supply are referred to in the art as “volatile” memory cells.
To overcome the deficiencies of volatile memory cells, so-called “non-volatile memory (NVM) cells” have been developed that do not require continued supply of power to the memory cells in order to maintain data storage therein. For example, so-called “Flash memory” is memory that employs field effect transistors. In Flash memory, the gate of the transistor is split into two separate gate structures, one being a “floating gate” and the other being a “control gate.” The floating gate is an electrically conductive, but electrically isolated (and, thus, a “floating”) structure. In other words, the floating gate is entirely surrounded by non-conductive material. The floating gate is sized and located, however, such that electrical charge can be applied to the floating gate by applying sufficient charge to the control gate to cause charge carriers (e.g., electrons) to “tunnel” through the non-conductive material surrounding the floating gate to the floating gate. Once the charge is removed from the control gate, the charge remains on the floating gate, until sufficient charge of opposite polarity is again applied to the control gate to cause the charge carriers on the floating gate to tunnel out from the floating gate through the dielectric material surrounding the floating gate. The charge on the floating gate is used to provide an electrical field in the channel region between the source and the drain, and that magnitude of the charge (and the resulting electrical field) is used to alter the electrical resistance between the source and the drain to characterize the transistor as exhibiting either a 1 or a 0 value.
It has recently been discovered that certain types of materials are capable of exhibiting what has been referred to as the “colossal magnetocapacitance phenomenon” or “colossal magnetocapacitance” under certain conditions. See, for example, J. Hemberger et al., Multiferroicity and Colossal Magneto-Capacitance in Cr-Thiospinels, Phase Transitions, volume 79, issue 12, pp. 1065-1082 (December 2006); R. P. Rairigh et al., Colossal Magnetocapacitance and Scale-Invariant Dielectric Response in Phase-Separated Manganites, Nature Physics 3, pp. 551-555 (2007); and R. F. Mamin et al., Giant Dielectric Susceptibility and Magnetocapacitance Effect in Manganites at Room Temperature, JETP Letters, volume 86, number 10, pp. 643-646 (2007). In essence, certain materials are capable of exhibiting a relative permittivity of about 6,000 or more. For example, certain materials may be capable of exhibiting a relative permittivity of about 10,000 or more, or even 100,000 or more. As used herein, the term “colossal magnetocapacitive material” means and includes any material capable of exhibiting colossal magnetocapacitance. As used herein, the terms “colossal magnetocapacitance phenomenon” and “colossal magnetocapacitance” mean and include the ability of a material to exhibit a relative permittivity greater than about 6,000, the magnitude of the relative permittivity exhibited by the material being variable by varying the intensity of a magnetic field applied to the material.